Why VFR Happens
Power fluctuations, wireless transfers, or background processes can lead to variable frame rate clips. Some mobile editors struggle with these, causing jitter or audio drift over time.
Solution on iPhone
- Re‑encode to HEVC at a constant frame rate that matches your timeline.
- Keep audio at AAC 48 kHz for consistent sync.
- Preview the first 30 seconds to confirm stability.
Suggested Targets
- Deliver 30 fps for general viewing; 60 fps for slow‑mo projects.
- 4K30: 20–35 Mbps | 4K60: 35–50 Mbps
How to Spot VFR Issues
- Audio gradually drifts out of sync on a long clip.
- Timeline scrubbing feels stuttery despite stable footage.
- Exports vary in duration slightly compared to the source.
Normalize first, then edit. You’ll avoid chasing sync bugs and get smoother exports that play perfectly on any device.